This invention relates to an automatic pencil apparatus for an automated drafting sytem.
An automated drafting system having a drafting head driven by a linear pulse motor or the like and which runs on a drafting paper so as to plot drawings and symbols has been developed. Such a drafting system is already available for practical use.
For these automated drafting systems, drawings were frequently desired to be drawn in pencil lead as usual erasable drawings. However, there was no profitable mechanism which gives the optimum pressure on the lead so as to plot smoothly on the paper and enables removal at the end of drawing lines, and which can slide the lead succesively in response to the abrasion of the lead.
This invention aims to solve the above problems in the combination of a gripping mechanism which holds the lead and lifts it up to a predetermined height, the gripper driving mechanism which actuates the gripper to hold and lift the lead and to release a lead, and the pressing mechanism which gives constant pressure downward on the lead. In the present invention, when the gripping mechanism releases the lead, the tip of lead touches the paper under a predetermined pressure given by the pressing mechanism, independently of the abrasion of lead. On the other hand, when the gripping mechanism holds and lifts up the head, the apparatus according to the present invention enables removal of the lead from the paper. In the apparatus of the present invention, when the lead is used up, the pencil lead worn down is easily exchanged for a new lead.